BRAIN TEASERS

EVEN AS doctors have learned more about brain trauma, the definition of a concussion remains frustratingly vague. The injury is diagnosed through a mishmash of symptoms, some of which may or not be present in any particular case. Bone breaks have X-rays and muscle tears have MRIs, but no form of medical imaging has yet been able to quickly and reliably confirm a concussion diagnosis. But a number of promising tests are in the medical pipeline.

Last month the U.S. Army, in partnership with the Alachua, Fla.--based company Banyan Biomarkers, announced a potential breakthrough in the development of a blood test for brain trauma. The test—which accurately diagnosed traumatic brain injury among 34 patients in a study conducted by Banyan and the Army—identifies substances that spill into the blood from injured brain tissue. For example, the proteins SBDP145 and SBDP120 appear to enter the blood as a result of damage to brain cells. "It's going to change medicine entirely," says Col. Dallas Hack, an Army doctor and the director of the Combat Casualty Care Research Program. The next step is a study of 1,200 patients that will take several years to complete.

Randall Benson, a neurologist at Wayne State in Detroit who has studied former NFL players, is hopeful but cautioned that the biomarker test results are preliminary. "The data look very compelling for moderate to severe injuries, but for mild injuries they have very little data," he says. Benson himself has been working on technology that may lead to effective and immediate diagnosis of mild brain injuries using a special type of MRI called diffusion tensor imaging, which creates images of water flow in the brain and could pick up anatomical irregularities.

In addition to diagnostic tests, advances in genetics suggest a way to predict how well a person will—or won't—recover from a concussion. A burgeoning field of research suggests that people who carry one or two copies of a version of a gene known as ApoE may be at increased risk of suffering brain-trauma-induced dementia. The ApoE4 variant (one of three common variations that a person can carry) is known to increase an individual's risk of developing Alzheimer's. However, the gene increasingly appears to have a role in slowing or preventing recovery from all manner of brain injury. For example, car accident victims who have the ApoE4 variant are more likely to die or suffer long-term brain damage. And studies of boxers and football players suggest that ApoE4 carriers take longer to recover from head trauma and are more likely to suffer serious dementia later in life.

In 2002, Barry Jordan, then chief medical officer of the New York State Athletic Commission, considered screening all boxers for the ApoE4 variant before deciding that more study was needed. As with biomarker research, genetic screens are a potentially promising tool in the fight against athletic brain trauma—but the science is in its infancy.

ONE PROMISING TEST IDENTIFIES SUBSTANCES THAT SPILL INTO THE BLOOD FROM DAMAGED BRAIN TISSUE